What to Know: The Invasive King Ranch Bluestem Weed

Have you noticed the lanky grass on the medians above the grass line? Have you ever thought to yourself, "Why won't the city cut our grass more often?" The answer isn't that simple. What you've noticed is the King Ranch Bluestem weed — a weed the entire state has been at war with for years.

When King Ranch (or KR) Bluestem (Bothriochloa ischaemum var. songarica) was introduced from Europe and Asia in the 1920s and 1930s, it was a desirable species for erosion control. The plant, by its nature, is drought resistant and quickly establishes itself by growing an average of one foot per week. It may have been too effective as it is now considered invasive and its presence threatens the abundance and diversity of native species. Facilities Operations Manager Clif Spangler describes the grassy weed as a nuisance and almost impossible for the city to control from a financial perspective.

The City of Arlington is currently on a three-week mowing cycle schedule for medians and rights-of-way. During the spring and summer, the grassy weed is typically not an eyesore. However, as fall approaches with decreasing daylight hours, KR Bluestem begins to seed out producing long dangling seed heads that can grow at an unbelievable rate of two to three feet in height within seven to 10 days. The introduction of a weekly mowing schedule during the fall months to combat the Bluestem seed heads would be extremely expensive. The cost to mow medians and right-of-ways in Arlington is about $50,000, per cycle. An additional four to six mowing cycles would cost an estimated $200,000 to $300,000 a year.

Chemical applications have also been found to be ineffective against KR Bluestem. Many cities across Texas have tried chemicals such as of MSMA (Monosodium Methyl Arsenate), with minimal success. The damage to the natural environment has helped rule out chemical applications as a defense against the KR Bluegrass.

For the time being, it looks like there is no effective answer to combat the KR Bluestem that is dominating the State of Texas. The only sure-fire way to end the Bluestem infestation is cold weather; therefore, until we get a good frost or two, we won't see the end of it.